After make a Nether Portal, I enter in it. After few second I was came to the Nerther but I didn't see my Portal. After walking around, I come back to my Portal and it have loaded but with only 2 Obisidian on top and below, the middle is 2 Portal Block. After take a screenshot, I enter the Portal and it generated a new Portal in a stranger place I nerver come. It far from my base about 4500 block ! ( I play in old world that I created in verision 1.17.0 )